The movie begins by showing students moving out of the school to the playground. A girl, Kurumi trips and falls while running as she takes a glance at Katsuragi-Kun, a fellow student. She goes to the school clinic to get treated. Mrs Sakami, the teacher in the clinic admits that she notices how Kurumi always looks at Katsuragi-Kun. Takeya, another student overhears their conversation and chips in. Mrs Sakami tells her to leave as it seems she has gotten better and before Takeya leaves, she calls Mrs Sakami Megu-nee. When Kurumi also leaves, she also calls Mrs Sakami Megu-nee. While Kurumi gets her bike as she gets set to go home, Katsuragi-Kun approaches her and asks about her leg. They both walk home together that day. The next day, Kurumi hurries to Mrs Sakami’s office to tell her that she went home with Katsuragi-Kun the previous day. Takeya who was eavesdropping tells her to express her feelings. Wakasa, the horticulture president comes to call the attention of Mrs Sakami and the two girls leave her office. The next day, as students arrive at the school, Kurumi, Takeya, Rii-san and Mrs Sakami gather together to eat. The four of them go to the roof to get vegetables and when they return, Takeya Yuki goes into a classroom to talk to some girls. But in reality, there is nobody there and the class is kinda a mess and also stained with blood. Outside the school, a lot of students are seen walking around but they have become zombies.
Kurumi and Rii-san make a plan to go outside the school premises to get resources. On their way, they see Takeya in a classroom. They encounter a group of zombies on the way but they distract them by using table tennis balls. They are later discovered by a smaller group of zombies that tries to attract them but Kurumi fights them off. The duo get to their destination which is the cafeteria and Rii-san begins to take what they need. Kurumi hears movement in the storage of the cafeteria and moves towards that direction gently and holding her weapon firmly. Turns out it is from a girl who identifies herself as Naoki Miki. They take her back to where they stay and check her for any injuries. Yuki introduces herself and the rest of the “School living club” to Naoki. Rii-san asks Yuki to look for a new uniform for Naoki and she leaves with Mrs Sakami. Rii-san then asks Naoki if she is the only one who survived on the north side of the school and Naoki says there were others in the beginning. Rii-san tells her to rest for a while as she takes her to where she’d stay. Later that night, they all eat spaghetti together. The next day, Yuki shows Naoki the view from the rooftop. Yuki says that the view is beautiful and Naoki is surprised at the statement because all they can see are zombies walking around. They both go to the broadcast room and Yuki talks to someone about Naoki but in reality, nobody is there which surprises Naoki again. Naoki goes to meet Rii-san and Kurumi to ask them why Yuki acts that way. They tell her that in her memory, the incident never happened and that both the students and teachers are alive in her memory. They beg Naoki to act along with Yuki but Naoki secretly tries to run away as she steals their properties. Kurumi catches her and tells her that leaving the school is a bad idea. Naoki tells her to let them leave together as no one might come to save them. Rii-san tells the story of when the incident happened and how they got to meet each other. The flashback shows Katsuragi-Kun getting bit while trying to save Kurumi. When Katsuragi-Kun turns into a zombie after he gets bitten, he attempts to attack Kurumi but she hits him on the head with a shovel. Only Kurumi, Rii-san, Yuki and Mrs Sakami were left alive and they formed the School Living Club. The next day, Naoki plays music from the broadcasting room to divert the attention of the zombies away from her route to escape. Yuki sees her and follows her, trying to persuade her from going. Rii-san and Kurumi go to turn off the music from the broadcast room. Kurumi quickly heads back to look for Naoki. Meanwhile, Naoki and Yuki get surrounded by zombies and they try to attack them. They climb on top of a car as they try to escape the zombies. Naoki then has a panic attack as the situation she is in reminds her of what happened when she was in the cafeteria. Kurumi arrives and makes a noise by hitting her shovel on the floor as she tries to draw the attention of the zombies. Rii-san then goes to the broadcast room to play the sports week song. Kurumi then tells the duo to run towards the classroom. As they run, both Naoki and Yuki imagine they are running a race with other students cheering them up. Later that day, Yuki goes to meet Miki to cheer her up and convince her to join the school’s living club. After a while, Kurumi and Miki go to try to fight off the zombies in the school storage room. As they fight the zombies, Miki sees her friend Kei as one of the zombies and she is frightened and falls to the ground but Kurumi kills the zombie. As they rest, Miki tells Kurumi that she admires her courage as she can fight any zombie even if it is her crush. Miki says that she heard it from Rii-san and she adds that she can only fight the zombies if it is a student she doesn’t know. The members of the school living club go into the storage area and are joyful as they find a lot of resources in the room. as they arrange the resources, a zombie appears and Kurumi tries to attack it. But the zombie shares a little resemblance with her crush and she gets frightened and falls to the ground but Rii-san helps kill the zombie. She goes to the top of the roof where Katsuragi-Kun was buried and she remembers as he tells her that he joined her club because he wanted to see her more. She breaks into tears and Rii-san tries to comfort her. That night, the four students take pictures of each other. In the following days, the group get so close to each other as they do everything together and played together.
One day, the four students stand on the roof and they decide to hold a school festival since it’s the autumn season. Rii-san tells the rest of the students that she would go to take permission from Mrs Sakami. When Rii-san gets to Mrs Sakami’s office, she tells Mrs Sakami that Yuki and Miki are forming a great relationship. She adds that Kurumi has helped them make the School safer and more secure. Mrs Sakami then asks Rii-san how she is doing. Rii-san replies that even though she is scared of what might happen to them in the future, She is fine. Mrs Sakami tells her that the strength of each of them compliments the others and that if they all work together, there is nothing to be afraid of. That night, while the four students are together, Yuki says that she doesn’t want to graduate but Rii-san tells her that they have to do it sooner or later. Miki asks them what they want to do when they graduate. Rii-san replies that she wants to go to college and Kurumi says she wants to become an athlete Miki tells her that she surely would be one. Miki says she also wants to continue her study. Yuki then tells the others that they should all go to the university together and they will occasionally visit Mrs Sakami. They all promise to remain friends no matter what.
Yuki goes to call Mrs Sakami to the classroom where they hold the school festival. Meanwhile, as they celebrate the school festival, unknown to them, A zombie picks up a lighter and turns them off and on. While the group tries to have fun as they read each other’s future, the fire alarm rings and the zombies are drawn towards the school building. They try to look for the source of the fire and they find out that the zombies are reacting to the noise of the alarm. They go downstairs and find out that one of the zombies set itself on fire. The zombies break through the barricade and try to attack the girls. They get separated as they all run in different directions. Miki and Rii-san run back upstairs and tries to wait for Kurumi and Yuki but the zombies come close to them and they run to the north section of the building. Yuki loses her way and gets lost and Kurumi runs to the rooftop. She climbs on top of a chimney as she tries to escape the zombies. Miki and Rii-san run into a classroom and barricade the door with a table and a chair. Rii-san almost loses hope and tells Miki to go and leave her alone but Miki tells her that she can’t leave her. The zombies break through the door into the classroom and Miki and Rii-san have nowhere to go. Yuki almost gets attacked by a zombie on fire. Kurumi imagines that she is talking to Katsuragi-Kun and she tells him that she loves him. She almost gives up and Katsuragi-Kun tells her to never give up. He puts a hand band on her hand and in reality, the hand band is in her hand. She stands up and tells herself to never give up and then jumps over the zombies to the ground. She picks up her shovel and attacks every zombie on her way. She goes to the classroom that Miki and Rii-san hid and she sees a zombie that looks like Miki on the floor. She starts to cry as she thinks Miki is dead. She then hears a noise from the room close to her and she hurries there. She sees Miki and Rii-san trying to fight some zombies and she helps them. She gets bitten by one of the zombies but it so happens that the zombie bit her hand band. They notice that Yuki is missing and they reassure themselves that she is alive because she is with Mrs Sakami. Yuki wakes up on the floor and goes into a room. She sees her teddy bear’s ear and then she remembers that Mrs Sakami was bitten by a zombie when they tried to pick some useful things. Then she sees Mrs Sakami as a zombie in front of her. Kurumi, Miki and Rii-san hear Yuki’s voice from afar off and they move in that direction. When they get there, they see that Mrs Sakami tied herself up so that she won’t be able to hurt anyone. Kurumi tells her that she can rest now and then kills the zombie.
They access the damage and they see that the warehouse has been burnt. Yuki tries to act as if nothing happened but Rii-san stops her. She then confesses that she knew all that was going on but acted as if she didn’t know. Then they all decide that it is time to graduate and leave school. They plan to hold a graduation ceremony to say thank you to Mrs Sakami and the school. At the ceremony, they all read the opening speech in tears and after that, they each give themselves their certificates. They leave the school the next day in Mrs Sakami’s car with Kurumi driving. As they pass through the streets, they see that the whole town has been infected. They decide to check by the university first before they go anywhere else.